SCSI strangeness

Before I get into exactly whats happening, lemme give you all a rundown on
my setup:
DTC 3510A scsi adapter
teac r55s cd-r
obsd 2.5 (generic kernel)
When I boot up, everything is detected and assigned devices ok (It sees the
burner, spits back the vendor and model information, assigns it to cd0,
etc.), but whenever I try to use the drive, whatever software I use to do
so (tosha, scsi, cdio, etc.) hangs, goes into a 'D' state (as indicated by
ps) and can only be terminated by rebooting the machine (kill -9 doesn't,
killing its parent shell doesn't even work). Does anyone know what's
causing this, and more importantly, how to fix it?
-------------------------------[ Cogent Software
William Osmond (william@cogent.net)
Technical Support
234 E. Colorado Blvd. Pasadena CA 91101 ste. 725
PH: (800) 733.3380x114 FAX: (626) 585-2785